let now = new Date();
console.log(now);  //2022-07-01T11:30:20.588Z

// 1. Date.parse();
console.log(Date.parse('5/23/2019'));  // 1558540800000
console.log(new Date(Date.parse('5/23/2019')));  //2019-05-22T16:00:00.000Z
console.log(new Date('5/23/2019'));   // 2019-05-22T16:00:00.000Z  Date会自动调用Date.parse

// 2. Date.UTC()
console.log(Date.UTC(2018, 1, 22));   //1519257600000
console.log(new Date(Date.UTC(2018, 1, 22)));  //2018-02-22T00:00:00.000Z

// 3. Date.now();
console.log(Date.now());
